The stupid spark plug is dry, need a carb airflow diagram pl

[Srinath]

OK I got spark, I got compression, I got suction, I got everything, in fact the stupid bike ran like a cheetah chasing a wounded buck till the bloody thing stalled on the off ramp.

The carbs are clean ... or if they are dirty I dont know where it is dirty ...

The spark plug is dry. as a bone. Dry.

WTH ...

Cool.
Srinath.

[arry_b]

Are you still running the mechanical fuel pump. Dump it if you are, and run a hose from fuel tape straight to the carb.

My UK 1998 model's run brilliantly for the last eight years since I did.

[Srinath]

Its got a short hose from the fuel tap to the carb.
However I am running it - trying to run it off a remote tank and the line is clear and taking on fuel. I mean there is fuel in the bowl, there is air and fuel flow in the air screw passage ... tomorow I will clean the passage from the pilot jet to the air screw, that's my only suspect passage @ this point.
Cool.
Srinath.

[Linegeist]

When this happened to me a couple of years ago. The problem on that occasion was that the float valve had jammed shut due to a build-up of petrol-derived gum.

I found this out by lucky accident at the side of the road when, in puzzlement more than anything else, I gave the carb a sharp rap with a 13mm spanner, which jarred the float valve loose and, to my surprise, fuel started flowing again. The bike started right up and ran perfectly for the rest of the day.

A carb strip the following weekend revealed the culprit and added to my education.

[DAVID THOMPSON]

in the 10 years i have been riding my mz bikes 80 percent of the problems i have had
with any of them running
HAS BEEN BAD GAS
on a trip the gas was so bad i had to have the son come and get me and the rt125
it was like some one had pored olive oil in it
dave

[Srinath]

The oblique fuel passage is now clean, I dunno if it was clogged before ... maybe I wish but, maybe not. Then I am screwed ...
Anyway I will re try with fresh gas.

The fact the plug is dry means no fuel is getting to the cylinder. I have a float bowl full of fuel, I know for sure ... so its getting into the bowl ... bowl to cyl, @ startup and idle the only way it gets there is via pilot jet and the air screw and the passage between them.

Bad gas, usually would get the plugs wet wont it - carbs work via bernouli's principle, not evaporation, you can put plain old water in the float bowl and you will suck that into the cylinder, but not fire obviously it can only burn somehting that is atleast mostly gasoline ... Oh I get a misfire every 3-4 start attempts ... so some gas is getting in just not enough. Again points to oblique passage IMHO.

I'll try with fresh gas ... the bike got suction, compression, valves are timed well, I am not sure its got the greatest spark, but in sunlight I can still see it sparking ... so my thought, it was the oblique passage ... I wish I chould have chased it with a wire, but its not possible to do that without drilling out the stopper plug under the intake mouth, and then I'd have to drill and tap it in that tiny size and install a tiny screw etc etc etc ... PITA.

Cool.
Srinath.

[Srinath]

I had the original pilot jet reamed to larger than .46 mm. Can anyone tell me if that is going to be disastrously rich ?
Cool.
Srinath.